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POPULAR SCIENCE REVIEW. 
he cannot. The eye is so much the pupil of the mind. We 
have ourselves known instances in which first-class wood en- 
gravers^ ignorant of the appearances of anatomical specimens, 
have so far deviated from the drawings set before them as 
absolutely to convey an idea of structure totally opposite 
to that which the artist intended to delineate. Indeed we 
apprehend that this is one of the reasons why there is so 
much discrepancy of opinion as to the arrangement of the 
minute particles which compose the tissues of animals and 
plants. The anatomist is seldom satisfied with the work of 
the engraver. 
The difficulties which we have hinted at, and which arise 
from the circumstance that it is impossible for two indi- 
viduals to work out one idea in exactly the same way, are 
obviated by the discovery of Mr. Hitchcock. The artist, be he 
never so clumsy in the use of the graving tool, may henceforth 
be his own engraver, for the simple reason that in using the 
pencil, he is absolutely preparing a block. The circumstance 
which led to the discovery of the graphotype, gives a good 
idea of the nature of the new method, and affords a proof of the 
truth of the old adage, that necessity is the mother of invention . 
In the summer of 1860, Mr. De Witt Clinton Hitchcock, one 
of the foremost draftsmen and engravers of New York, was 
engaged in making a drawing upon boxwood. In the course 
of his operations he found it necessary to erase a portion of his 
sketch and re-whiten the block. Now the white surface of 
blocks for wood-engraving is composed of a material similar to 
that of the enamel which we find on visiting-cards, and one of 
these latter was employed by Mr. Hitchcock in renewing the 
surface. The card he employed happened to be one printed 
from a copper-plate, and in rubbing off the enamel with 
the aid of a brush and water, he found to his astonishment 
that the printed letters remained in relief, and were not re- 
moved by the action of the brush. In point of fact he had 
accidentally produced a sort of block upon which stood out the 
letters of the original copper plate. The ink by combining 
with the enamel had been enabled to resist the action of both 
water and brush, and thus the elements of the new discovery 
were laid before the artist's mind. Surely, he said, “ if I pre- 
pare a surface of prepared chalk, draw upon it with ink, and 
then brush the surface, my drawing will ‘ come out 3 in relief. 
All that I shall then have to do will be to harden the chalk, 
and I shall have a block for printing. He tried the experi- 
ment and he succeeded." He took a slab of chalk, and having 
reduced its surface to as smooth a condition as possible, he 
drew upon it with an ink composed of silicate of potash 
(water-glass) and indigo, and when the sketch was dry, he 
